Reference is hereby made to the following copending applicaton, the benefits of whose filing date is claimed: application Ser. No. 463,487, filed on Apr. 24, 1974.
Conventional letterpress and lithographic presses apply ink to the printing surface by contacting the printing roller with an inking roller, sometimes referred to as the form roller, to thereby maintain a supply of ink on the printing surface. Most printing masters are sensitive to the thickness of the ink applied to them. If the roller supplying ink to the master carries an ink film that is not uniform, the non-uniformities are carried to the resulting print. Conventional presses using such inking systems suffer from a disadvantage in that the inking roller retains a memory, or ghost, of the last image printed. This is the case because on each inking cycle the master extracts about half of the film of ink in the printing (character) areas. The differences in ink film thickness between image and background areas immediately after this extraction is reduced by a factor of two when the form roller is re-inked from the ink supply train. Nevertheless, under some conditions, a detectible and objectionable "ghost" is seen in the subsequent print.
In addition to print-by-print ghosts, longer run non-uniformities exist when the ink is consumed more heavily in some areas than in others. This can be corrected by careful adjustments in ink delivery to match any non-uniformity of consumption. A long response time to reach equilibrium makes such adjustments time consuming and wasteful.
It is an object of the present invention to provide a novel process for the inking of printing surfaces.
A further object is to provide such a process which is especially useful when the printing surface is in the form of a roller or drum.
An additional object is to provide such an inking process in which the aforementioned "ghosting" problem is reduced or eliminated.
Another object is to provide such a process which eliminates the problem of long response times in adjusting ink delivery to match non-uniformity of consumption.